Health workers are key potential leaders in the struggle to contain the HIV/AIDS pandemic. This innovative research will test for wider dissemination a model of an effective HIV prevention intervention in Malawi, one of the poorest countries in Africa, where one in seven adults is HIV positive. This intervention is based on the primary health care and social learning models. Health workers will be mobilized as rural community leaders who will involve a community in a peer group intervention for HIV/AIDS prevention. The intervention is implemented in four phases using a train-the trainers model. In Phase 1, health workers at a district hospital will be trained as community leaders through participation in the peer group intervention. In Phase II, at a selected rural health clinic and the cluster of villages it serves, the trained district health workers will train clinic health workers and interested local leaders as community peer group leaders. Training in Phase I and II will enable the district and rural clinic workers to change their own HIV prevention behaviors and to modify health services to be more supportive of HIV prevention. In Phase III the clinic workers will train community members as peer group leaders who then will offer peer group education and other activities to the entire community. In Phase IV, the program will expand to provide the knowledge and skills parents need to protect their children, thus enhancing young people's safer sex behaviors. The intervention will enable community adults and adolescents to practice safer sex behaviors. Hypotheses regarding changes in health workers, health service delivery, and community members' behaviors will be evaluated by comparing the intervention district with a similar control district at pre-intervention and at 16 and 32 months after Phase I using observation and records of health services, interviews with health workers and clients, and sample surveys of community adults and adolescents. A sample of 1100 each (550 adults, 550 adolescents) in the intervention and control community will provide adequate power to test hypotheses about key behavior changes for adults and adolescents separately. At 16 months after Phase 1, we expect substantial changes in health workers and health services, but the intervention may not have diffused sufficiently to result in community-wide differences. Significant increases in safer sex behaviors are expected at 32 months after Phase 1. The project will strengthen research capacities of the collaborating college of nursing and the district and rural clinic health workers. Low cost and use of existing infrastructure facilitate high transferability.